This slide shows a stained whole mount of the Oriental liver fluke (Clonorchis sinensis), an important trematode parasite of the humans in many regions of Asia, especially China, Southeast Asia and Japan.  Humans are infected by eating raw or poorly cooked fish containing the encysted metacercariae.  After being ingested, these cysts dissolve in the intestine, releasing the young flukes which then migrate to the bile duct and liver.